Tribological properties of PVD amorphous carbon coatings micro-structured by picosecond laser ablationMittwoch (26.06.2019) 18:25 - 18:45 Uhr
The reduction of wear is an important requirement in engineering with estimated direct costs of about 1 - 4 % of the gross national product. Therefore, the increase of the service life of metallic components subjected to dynamic-mechanical loads is of great industrial importance. The present study deals with a reduction of friction and wear by application of micro-structured low friction hard amorphous carbon coatings. Graded Cr/CrNx/(Cr,C)y/a-C:H:W/a-C:H hard coatings with a thickness of approx. 2 µm were deposited onto hardened and polished X153CrMoV12 cold working steel substrates by reactive magnetron sputtering. These coatings were micro-structured by laser ablation using a picosecond laser system with a wavelength of 1030 nm and an average pulse energy of 30 µJ to 200 µJ. The tribological behaviour of these micro-structured coatings was studied by pin-on-disc tests against aluminum pins under both oil lubrication and dry conditions. The diameter of the laser ablated microscopic holes, so-called dimples, was varied between 50 µm, 100 µm and 150 µm at a constant degree of coverage of about 40 %. The coefficient of friction and the wear rates of the coatings and the aluminium pins were determined after 20,000 cycles. The wear due to adhesion was studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX).